It is perfectly possible, even without Filesystem support. Just convert the file to a byte array (I don't just mean read it into memory either, I mean store it in a class as a byte array), then when it is in a byte array, you can read it at runtime and interpret
it, however, you would have to have advanced graphics support, as most TrueType Fonts require you to be able to draw straight lines (admittedly simple), but also to draw quadratic Bézier curves and there is still a lot more you'd have to account for
in a *.ttf file.
I had an idea similar a few weeks ago, I then gave the idea up when I saw the amount of work I would have to do to get it working, when I had more pressing things to work on. Kudos to you if you can get it working.
Here is a few links to help you out: